Lamps are instruments used to produce, disperse or alter distribution of light, and may comprise hanging lamps, wall lamps, and ceiling lamps, etc. Hanging lamps are very often applied to a ceiling of, for example, a garage. A hanging lamp may comprise a frame and one or more light emitting modules. The number of light emitting modules may be determined according to the size of interior room space. Existing hanging lamps are attached to a ceiling through either a holder or a hanging wire. These two approaches to secure hanging lamps to a ceiling possess distinguishing characteristics. A Lamp secured by a holder may be more stable and less subject to waggling movement. A Lamp secured by a hanging wire may be adjustable in height depending on interior room space to reach a preferable illumination effect. However, existing hanging lamps are limited to either one of these two approaches, leaving a user no option to choose between alternate approaches based on his or her actual needs. Existing hanging lamps also suffer from an inability to adjust the emitting angle of their light emitting modules once installed. A favorable illuminating condition would be difficult to achieve if the installation position of a lamp on ceiling is limited due to small interior room space.